Water softening process



Patented Apr. 23, 1940 2,198,381

UNITED STATES PATENT orrici'.

WATER SOFTENING PROCESS Carleton Ellis, Montclair, N. .L, assignor to Ellis- Foster Company, a corporation of New Jersey No Drawing. Application June 2, 1937, Serial No. 145,986

Claims. (Cl. 210-24) This invention relates to the softening of water i. e., the purifying agent throws ofl color into by treating said water with a bed of non-colorthe water. Also, the growth of fungus in the throwing organic filter material which has base-exchange medium (which might be brought marked base-exchange properties, and which is about by allowing the apparatus to stand idle or 5 immune to growth of molds. Such filter mateindeed might occur in certain parts of the bed rial can be produced by treatment of organic even while normal operation was taking place) material including tannins, tannin-containing would be liable to clog the filter bed, seriously wood extracts (also including sulphite cellulose lower the capacity of a water-softening unit, and waste liquor solids made from woods containing also attack the water-softening medium itself.

tannin), with acid sludge produced as a by- Furthermore, it is obvious that such materials l product in the refining of petroleum oils, which woul be of little value in connection with waters sludge contains sulphuric acid, sulphurous acid, containing pathological organisms. sulphonic acids, and organic materials taken up The materials of the present invention which from the oil being treated. During said treatare the insoluble reaction products of petroleum ment it is advisable that the temperature be sludge and wood extracts of the kind herein set 1 caused to rise to at least about 80 or to a higher forth, are not subject to these disadvantages. No temperature such as 150 C. Some heat will be trace of mold has ever been observed by me to liberated by the chemical action. have grown on any of these sludge-insolubilized It is a primary object of the invention to prowood-extracts. Further, if properly made, they vide, for water-softening, filter beds which possess will not give any color to water passing through 5 the quality of base-exchange to a marked degree. a bed of the material, by a leaching occuring dur- It is also an object of the invention to produce ing the step of passing the water through the filter beds of organic base-exchange materials mass. If a tendency toward this condition is nowhich will not support the growth of those ticed, it may be overcome by carrying out the saprophytic species of fungi known as molds, insolubilization to a greater degree as for ex- 5 e. gi., Penicillium or Aspergillus. ample by allowing the acid (e. g. acid sludge) to It is a further object to obtain a filter bed react at higher temperature or for a longer time, capable of softening water which will regenerate on the wood extract.

rapidly and which will require a minimum of In the p ration of zeolite [wat -s t n n water to wash out excess regenerant and ions for plants, the wash water requirement is an item 5 which the regenerant has base-exchanged. of considerable expense. This water is that Another object is the preparation of an organic which is required immediately after the regenerabase-exchange filter bed which is not color throwtion step in order to wash out excess regenerating ing, that is, one which will not discolor water fluid and also those ions causing hardness which passin through it in the normal water-softening are now in solution by virtue of the base-exg cycles. change reaction with the regenerant. This water Adams and Holmes have described (British is of course Wasted, and the cost has been shown h Patent 450,308) a water-softening synthetic resin by J. H. Walker and L. F. Collins (Industrial and s which is obtained by condensing polyhydric Engineering Chemistry, 21, 1020 (1929)) in the phenols with formaldehyde. If such material is case of the installation at the Beacon Street 4 stored for a few days in a moist condition, ire- Plant of the Detroit Edison Co. to represent quently it soon becomes covered with .a char- 10.2% of the operating costs. A. S. Behrman acteristic greenish-gray moldy growth. Further, (Journal of the American Water Works Assoif the material is allowed to stand with a superciation, 26, 618-28 (1934)) estimates the n r al natant layer of water, the liquid sometimes bewash-Water requirements of a synthetic zeolite 4 comes moldy on the surface and throughout the to be 5 to 10 per cent of the total volume of liquid and the lower layer of resin also becomes water softened, and that of a greensand zeolite moldy. At the same time, the water layer may to be 20 to 25 per cent.

become quite highly colored because of an orange- I have found by experiment that the wash water so brown substance that apparently leaches out of requirement for the materials herein described is 5 the resin. less than 5 per cent of the total volume of water These changes are unsatisfactory because a treated. colored efiluent would be generally undesired and In preparing these materials I may take, for

unsatisfactory. This property of coloring the example, chestnut extract, quebracho extract, water is termed in this art, color-throwing}? cutch, hemlock extract, or the raw plant products g pm which they are derived, waste celluloseilphite liquor or other tannin-containing wood (tract, and add it with stirring to from 2 to 10 mes its weight of acid sludge from petroleum :fining. Depending on the specific materials sed, the temperature, concentrations, and nount of moisture present, a reaction takes ace which may liberate a sufficient amount of eat to cause a sharp rise in temperature. Agitaan and a sufiiciently large vessel to hold any am produced are recommended. I prefer to rep the temperature within the limits of 60 to C. and a desirable mean temperature is "-90" C. The temperature should not rise to 'er 150 C., in any case, or the base-exchange 'operties of the material will be substantially duced. Any of the known methods such as tificial heating or cooling, dilution with water other appropriate solvent, or choice of rerents or raw materials may be utilized to this vd. A desirable type of sludge is one obtained 3m white oil refining. A typical sample of this aterial is a black, viscous liquid having an odor sulphur dioxide and a specific gravity of out 1.4. I prefer to so adjust the temperature, conntrations, and time of reaction that the product substantially wholly insoluble in water. If the mperature is kept too low, the product remains tter-soluble; if the temperature is too high, the se-exchange capacity is reduced. At 80-90 C. e reaction is usually suificiently complete in 10 30 minutes. When the reaction is finished I 1y allow the material to cool gradually to room nperature or may arrest the reaction by coolg, and conveniently by pouring the charge into relatively large volume of water, this also servg to partially wash the product free of any cess of reagents. It is not absolutely necessary wash at this point, as the washing step may be rried out after drying. If placed in water, wever, the solids are separated by a suitable aans such as filtration or decantation, and furer washed if desired. Although the material 1y be used while still wet but washed substan- .lly free of excess reactants, I prefer to dry it, this serves to improve the granule characterics such as porosity and crushing strength. 1e freshly precipitated product is ordinarily of variety of particle sizes. It may be crushed or aund and classified by screening, and this may 're place before washing so that the latter procs is facilitated; but screening may be accomshed more successfully after drying. Also the )6); may be extruded, dried and comminuted to e desired filtration-granule size. The yield of finished material is remarkably gh, being about 60% of total input by weight 1811 4 parts of sludge (of which as much as 30% 1y be water) are used with 1 part of the solids the waste liquor left from cooking hemlock lod in the usual sulphite cooking liquor. The troleum sludge contains sulphonic and sulurous acids, as well as other substances iniding organic matter. That this combination acts with tannin-containing extracts to proce a high yield of water-insoluble product is expected, since sulphonic acids are water sensi 'e, and addition of sulphite is a common method rendering tannins more soluble, as may be ted in the processes of sulphiting quebracho tract or the production of sulphite pulp from od. A distinct advantage of the products of a present invention is their cheapness, since ldge is generally a waste product.

A suitable method of use of the water softening material is to place the classified material in an apparatus of the type commonly employed in zeolite water softening, to form a filter bed which will permit the water to run through by gravity or under pressure. The water to be treated is then led through the apparatus, and the base-exchange material remove's the undesirable ions. When the bed is exhausted it may be regenerated by running dilute acid, say 5% sulphuric, or sodium chloride brine through it. (Exhausted as here used, as in the prior art, means that the base-exchange material will not efficiently remove further amounts of the undesirable ions from the water.) It may be mentioned at this point that a desirable feature of the present products is that they may be regenerated with acid solutions without disintegration, whereas a similar treatment of ordinary zeolites would disintegrate the same.

The following examples are given by way of illustration and should not be construed to limit the invention as to scope or proportions.

Example 1.-One hundred parts by weight of dried hemlock sulphite liquor and 400 parts of white-oil sludge were thoroughly mixed and heated to 80 C. for minutes. The reaction mixture was allowed to stand while spontaneously cooling for minutes, when it was diluted with a large volume of water, filtered and dried at 110 C.

A sample which had been screened through 20 over mesh was placed in a glass tube 2 cm. in diameter to form a column 10 cm. high. This was tested with water containing 385 ppm. hardness (as calcium carbonate) and it softened an average of 2100 cc. of water using 300 cc. of 10% sodium chloride for regenerating. After each regeneration cycle, an average of cc. of water were required to be run through the column before the eflluent was soft. This is about 2.3 per cent of the volume of water softened.

Example 2.One hundred parts by weight of chestnut extract and 300 parts white-oil sludge were mixed and heated slowly to 150 C. The material gradually became more viscous and finally resembled a granular solid. It was washed in a large volume of water and dried.

A sample ground to pass through 20 on 40 mesh screens was placed in a glass tube 2 cm. in diameter to form a filter bed 10 cm. high. This was tested by passing water of 478 ppm. hardness downward through the bed. An average of 750 cc. were softened using 200 cc. of 10% sodium chloride brine.

The material was allowed to stand in contact with distilled water for 1 hour. No color, taste, or odor was detectable in the supernatant water.

Example 3.One hundred parts by weight of dried, powdered, sulphited quebracho extract were mixed with 500 parts of white-oil sludge. The mixture became warm and sulphur dioxide was evolved. It was heated to 80 C., held at that temperature for 10 minutes, allowed to cool to C., poured into a large volume of water, filtered, and dried at 120 C.

The product was tested as in the preceding examples with a solution of calcium sulphate containing 407 ppm. hardness. A total of 1650 cc. of the water were softened per cycle, using 200 cc. of 10% sodium chloride as regenerant.

It will be noted that in the above examples, the amounts of the acid material are given as 400, 500 and. 300, per 100 parts of the tanning extract used. The figures can vary to some exaieaei 3 tent. Proportions of the order indicated can be included in the expression several parts by weight (of the acid) to one part by weight of the extract.

Example 4. A solution of calcium bicarbonate containing 342 ppm. hardness (figured as. calcium carbonate) and 0.405 mg. bicarbonate ion per cc. was prepared and used to test the product of Example 1 which had been regenerated with 250 cc. of 5% sulphuric acid. The filter softened 1650 cc. of the water. After a second regeneration, 1850 cc. of water containing 406 ppm. hardness and 0.478 mg. bicarbonate ion per cc. were treated. In each case, the bicarbonate ion was destroyed by virtue of the hydrogen ion released from the base-exchange material when the calcium was absorbed.

Example 5 .In this example, formaldehyde and a quebracho extract were reacted to form a resin. Results obtained should be compared with those of Example 6.

One hundred parts by weight of a powdered quebracho extract were dissolved in 500 parts of water. The solution was diluted with 500 parts of water and 200 parts of 37% formalin and the mixture was h'eated to boiling. Sixty parts of concentrated hydrochloric acid were added and the entire mass set to a soft gel which was broken up, washed with water, and dried at 50 C.

After subjecting a sample of the granulated material to three exhaustions with calcium sulphate solution and three regenerations with 10% sodium chloride solution, the sample was drained and placed in a stoppered bottle for one week. At that time, the material was covered with a growth of mold.

Another sample which had been exhausted and regenerated as above was covered with ten times its volume of distilled water and allowed to stand at room conditions. After 24 hours the supernatant liquid was colored a light yellow. After 6 days the layer of liquid immediately above the resin was dark brown colored and the surface of the liquid was moldy. After one month, the entire liquid was dark colored and the mold extended throughout the liquid and on the solid resin.

Example 6.The products made as in Examples 1 and 3 were simultaneously subjected to the same conditions as the samples of Example 5 and no mold growth .or water coloration could be observed.

Samples of products of Examples 1, 2 and 3 were placed in 5 times their volume of distilled water. No mold growth occurred. The materials were inoculated with portions of the mold which grew on the quebracho-formaldehyde resin of Example 5. Growth did not continue on these new mediums, and after one weekthe portions of mold which served as inoculators had dried up and substantially disappeared.

Water softening agents of the type herein set forth, are claimed in my copending cases, Ser. No 119,131, filed Jan. 5, 1937, and Ser. No. 120,143 filed Jan. 11, 1937.

What I claim is:

1. A process of softening water having hardness, which comprises flowing said water in contact with a bed of non-color-throwing organit material which resists growth of mold, and which comprises the base-exchange substance produced by the action on one part by weight of a tannincontaining extract with about 2 to 10 parts of 2 sulphuric acid of a sufiicient concentration tc generate heat when brought into contact witl said extracts, and insolubilizing the solid reactior product by carrying the temperature to betweer and 120 C.

2. A process of softening water having hardness, which comprisesfiowing said water in contact with a bed of non-color-throwing organii material which resists growth of mold, and whicl comprises a base-exchange material produced b1 the action of several parts by weight of an acir petroleum sludge on one part by weight of a soli tan extract, in which action the temperature it brought to between 60 and 150 C.

3. A process of softening water having hardness, which comprises flowing said water in con tact with a bed of noncolor-throwing organi material which resists growth of mold, and whicl comprises a base-exchange material produced b; the action of several parts of acid sludge from petroleum refining on one part of the solids o waste cellulose sulphite liquor, at a temperaturl between about 50 and 120 C., for about 10 to 3* minutes.

4. A process of softening water having hard ness, which comprises flowing said water in con tact with a bed of non-color-throwing organi material which resists growth of mold, and whic] comprises a base-exchange material produced b1 the action of several parts of acid sludge fror white oil refining on one part of chestnut extrac1 at a temperature of about -90" C., for a tim which is a substantial fraction of an hour.

5. A process of softening water having hard ness, which comprises flowing said water in con tact with a bed of non-color-throwing organi material which resists growth of mold, and whicI comprises a base-exchange material produced b the action of several parts of an acid petroleur sludge on one part of a tannin, such reaction c acid on tannin being conducted at about 50 t C., for a time which is a substantial fractio only of an hour.

CARLETON ELLIS. 

